The invention relates to a coating device, comprising at least one evacuable recipient which is intended for receiving a substrate, at least one gas supply device, by means of which at least one gaseous precursor can be introduced into the recipient, and at least one activation device which comprises at least one heatable activation element, the end of which is fastened to a holding element at a fastening point, wherein a shielding element is present, by means of which at least the fastening point can be protected at least partially against the action of the gaseous precursor, the shielding element being of essentially cylindrical design, and there being arranged on that side of the shielding element which faces away from the holding element a closing element which has at least one outlet port. The invention relates, furthermore, to a corresponding coating method.
Coating devices of the type mentioned are intended, according to the prior art, for coating a substrate by means of hot wire-activated chemical vapor deposition. The deposited layers may comprise, for example, carbon, silicon or germanium. The gaseous precursors may correspondingly comprise, for example, methane, silicon tetrahydride, monogermanium, ammonia or trimethyl silane.
It is known from P. A. Frigeri et al.: “Hot Wire Chemical Vapour Deposition: Limits and Opportunities of protecting the tungsten catalyzer from silizide with a cavity”, Thin Solid Films Vol. 517, Iss. 12 (2009) 3427, that an undesirable reaction of the material of the activation element with the precursor takes place particularly at the relatively cold clamping points of the activation element. For example, the use of a silane compound as precursor may lead to the formation of silicide phases on the activation element. These silicide phases modify the electrical resistance, the surface quality and the mechanical load-bearing capacity of the activation element, and therefore, this often has to be exchanged after only brief use.
To solve this problem, said prior art proposes to protect a region around the clamping points of the wire used as activation element against the action of the precursor by means of a cylindrical high-grade steel element with a diameter of 4 mm and with a length of 90 mm. The service life of the activation element is thereby to be prolonged. Although the prior art shows such a prolongation of the service life, this is nevertheless still insufficient during long-lasting coating methods or for carrying out a plurality of shorter coating methods one immediately after the other.
Therefore, the object of the invention is to prolong the service life of an activation element in a coating device for hot wire-activated chemical vapor deposition.